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Explorer
Explorer
1,472 Views
Registered: ‎07-17-2014

On the problem of GTH master-channel

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hi, everybody
I have a little doubt about GTH's master channel.

According to the official document of Xilinx(ug576/ug476), there is a way of Multi-Lane when no RX Buffer is used.

 

1. When GTH is generated with IP-Catalog, why still has a master-channel option when you choose to use rx-bufferr?

11.png

 

12.png

 

2. With respect to master-channel, RXOUTCLK is a clock recovered from the received data from the main channel.
But when the main channel has no data, will RXOUTCLK be there?

Will it affect the normal reception of the other salve lane ?

 

13.png

 

 

 

 

 

 

 

 

 

 

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Moderator
Moderator
2,153 Views
Registered: ‎07-30-2007

Re: On the problem of GTH master-channel

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It seems unusual to have lanes acting independently but there is one possibility I missed .  You can run them all from the master channel if you have the buffer enabled and clock correction turned on.  When there is no recovered clock the RXOUTCLK would lock to the local reference clock and the difference in the frequencies would be compensated for with the clock correction. 

 

If your lanes are completely independent and there is no clock correction and no synchronous reference clock you need to instantiate 4 single channel instances of the wizard so that each will have its own clocking set up.




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Moderator
Moderator
1,432 Views
Registered: ‎07-30-2007

Re: On the problem of GTH master-channel

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If you are sending master and slave lanes they are sent as a channel and it is assumed the master lane will have data whenever the slave lane is sending data.  If the master lane data goes away the rxoutclk will lock to the reference clock which could be a problem for slave lane synchronization if the reference clock is not derived from the same oscillator that is sending the slave data.  If your master and slave lanes will be acting independently you cannot use them as a channel without a synchronous reference clock.




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Explorer
Explorer
1,404 Views
Registered: ‎07-17-2014

Re: On the problem of GTH master-channel

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@roym, thank you for your answer.
That is to say, if the lane on the sending side isn't in the same crystal oscillator,
for example, 4 lane on the separate board, then the receiver side can only use [RX buffer bypass in Single-Lane Auto Mode].
Because in the case of using rx-buffer, the default in IP-Catalog is the mode of multi-lane, and it seems that it cann't be modified. But there is no such problem when using GTX.

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Moderator
Moderator
2,154 Views
Registered: ‎07-30-2007

Re: On the problem of GTH master-channel

Jump to solution

It seems unusual to have lanes acting independently but there is one possibility I missed .  You can run them all from the master channel if you have the buffer enabled and clock correction turned on.  When there is no recovered clock the RXOUTCLK would lock to the local reference clock and the difference in the frequencies would be compensated for with the clock correction. 

 

If your lanes are completely independent and there is no clock correction and no synchronous reference clock you need to instantiate 4 single channel instances of the wizard so that each will have its own clocking set up.




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Explorer
Explorer
1,371 Views
Registered: ‎07-17-2014

Re: On the problem of GTH master-channel

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@roym
clock correction or 4 single channel instances, thanks for your two advice.
I hope there will be no problem in the practical application
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Moderator
Moderator
1,357 Views
Registered: ‎07-30-2007

Re: On the problem of GTH master-channel

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There is some room for misunderstandings on this.  You should be able to simulate your intended system with the example design and make sure it operates the way you intend.




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